A rat liver homogenate from a Sprague-Dawley laboratory rat that we infected with rat serum from a wild rat had an infectious titer (3.5 logs) too low to permit sequencing. The liver homogenate was inoculated into an immunocompromised scid rat to generate a stock with a ten-fold higher infectious virus titer. Attempts to clone the virus genome in an expression library have begun. We showed that our recombinant vaccine protected macaques against hepatitis caused by heterologous as well as homologous strains of HEV and we are awaiting results of a phase II/III clinical trial held in Nepal. We analyzed 14 chimpanzee monoclonal antibodies to HEV and identified 2 major antigenic sites and showed that one of them contained neutralization epitopes whereas the other did not. That information was used to develop a surrogate test for neutralizing antibodies that should decrease the need for challenge tests in monkeys. We showed that putative neutralizing antibodies cross-reacted with all 4 mammalian genotypes of the virus. We used our infectious cDNA clone of HEV to identify cell lines which are permissive for viral genome replication. We constructed replicons which express GFP or luciferase and are using them to study gene function. We have identified a cell line which can be infected with HEV and are trying to establish a neutralization test employing it.